Device to device (D2D) communication, or sidelink communication, refers to a direct communication mechanism between two user equipments (UE) without traversing a base station (BS). In order to synchronize a D2D device to the network or another device, a D2D synchronization signal may be transmitted from a synchronization source to align the timing among multiple devices. In a network consisting of D2D devices, a D2D device may receive multiple synchronization signals simultaneously. Thus there is a need for a method for selecting and forwarding the synchronization signal.